APPENDIX: SOME PROBLEMS IN THE PHILOSOPHY OF SCIENCE
2. THE ISSUE AT STAKE
All this looks like a great victory of philosophical critical thought over the 'naïve realism' of the physicists. But I doubt whether this interpretation is right.
Few if any of the physicists who have now accepted the instrumentalist view of Cardinal Bellarmino and Bishop Berkeley realize that they have accepted a philosophical theory. Nor do they realize that they have broken with the Galilean tradition. On the contrary, most of them think that they have kept clear of philosophy; and most of them no longer care anyway. What they now care about, as physicists, is (a) mastery of the mathematical formalism, i.
e. of the instrument, and (b) its applications; and they care for nothing else. And they think that by thus excluding everything else they have finally got rid of all philosophical nonsense. This very attitude of being tough and not standing any nonsense prevents them from considering seriously the philosophical arguments for and against the
Galilean view of science (though they will no doubt have heard of Mach 7 ). Thus the victory of the instrumentalist philosophy is hardly due to the soundness of its arguments.
How then did it come about? As far as I can see, through the coincidence of two factors, (a) difficulties in the interpretation of the formalism of the Quantum Theory, and (b) the spectacular practical success of its applications.
(a) In 1927 Niels Bohr, one of the greatest thinkers in the field of atomic physics, introduced the so-called principle of complementarity into atomic physics, which amounted to a 'renunciation' of the attempt to interpret atomic theory as a description of anything. Bohr pointed out that we could avoid certain contradictions (which threatened to arise between the formalism and its various interpretations) only by reminding ourselves that the formalism as such was self-consistent, and that each single case of its application (or each kind of case) remained consistent with it.
The contradictions only arose through the attempt to comprise within one interpretation the formalism together with more than one case, or kind of case, of its experimental application. But, as Bohr pointed out, any two of these conflicting applications were physically incapable of ever being combined in one experiment. Thus the result of every single experiment was consistent with the theory, and unambiguously laid down by it. This, he said, was all we could get. The claim to get more, and even the hope of ever getting more, we must renounce;
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7 But they seem to have forgotten that Mach was led by his instrumentalism to fight against atomic theory--a typical example of the obscurantism of instrumentalism which is the topic of section 5 below.
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physics remains consistent only if we do not try to interpret, or to understand, its theories beyond (a) mastering the formalism, and (b) relating them to each of their actually realizable cases of application separately. 8
Thus the instrumentalist philosophy was used here ad hoc in order to provide an escape for the theory from certain contradictions by which it was threatened. It was used in a defensive mood--to rescue the existing theory; and the principle of complementarity has (I believe for this reason) remained completely sterile within physics. In twenty-seven years it has produced nothing except some philosophical discussions, and some arguments for the confounding of critics (especially Einstein).
I do not believe that physicists would have accepted such an ad hoc principle had they understood that it was ad hoc, or that it was a philosophical principle--part of Bellarmino's and Berkeley's instrumentalist philosophy of physics.
But they remembered Bohr's earlier and extremely fruitful 'principle of correspondence' and hoped (in vain) for similar results.
(b) Instead of results due to the principle of complementarity other and more practical results of atomic theory were obtained, some of them with a big bang. No doubt physicists were perfectly right in interpreting these successful applications as corroborating their theories. But strangely enough they took them as confirming the instrumentalist creed.
Now this was an obvious mistake. The instrumentalist view asserts that theories are nothing but instruments, while the Galilean view was that they are not only instruments but also--and mainly--descriptions of the world, or of certain
aspects of the world. It is clear that in this disagreement even a proof showing that theories are instruments
(assuming it possible to 'prove' such a thing) could not seriously be claimed to support either of the two parties to the debate, since both were agreed on this point.
If I am right, or even roughly right, in my account of the situation, then philosophers, even instrumentalist
philosophers, have no reason to take pride in their victory. On the contrary, they should examine their arguments again. For at least in the eyes of those who like myself do not accept the instrumentalist view, there is much at stake in this issue.
The issue, as I see it, is this.
One of the most important ingredients of our western civilization is what I may call the 'rationalist tradition' which we have inherited from the Greeks. It is the tradition of critical discussion--not for its own sake, but in the interests of the search for truth. Greek science, like Greek philosophy, was one of the products of this tradition, 9 and of the urge to understand the world in which we live; and the tradition founded by Galileo was its renaissance.
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8 I have explained Bohr 'Principle of Complementarity' as I understand it after many years of effort. No doubt I shall be told that my formulation of it is unsatisfactory. But if so I am in good company; for Einstein refers to it as ' Bohr's principle of complementarity, a sharp formulation of which . . . I have been unable to attain despite much effort which I have expended on it.' Cf. Albert Einstein: Philosopher-Scientist, ed. by P. A. Schilpp, 1949, p. 674.
9 See ch. 4, below.
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Within this rationalist tradition science is valued, admittedly, for its practical achievements; but it is even more highly valued for its informative content, and for its ability to free our minds from old beliefs, old prejudices, and old
certainties, and to offer us in their stead new conjectures and daring hypotheses. Science is valued for its liberalizing influence--as one of the greatest of the forces that make for human freedom.
According to the view of science which I am trying to defend here, this is due to the fact that scientists have dared (since Thales, Democritus, Plato Timaeus, and Aristarchus) to create myths, or conjectures, or theories, which are in striking contrast to the everyday world of common experience, yet able to explain some aspects of this world of common experience. Galileo pays homage to Aristarchus and Copernicus precisely because they dared to go beyond this known world of our senses: 'I cannot', he writes, 10 'express strongly enough my unbounded admiration for the greatness of mind of these men who conceived [the heliocentric system] and held it to be true . . ., in violent opposition to the evidence of their own senses. . . .' This is Galileo's testimony to the liberalizing force of science.
Such theories would be important even if they were no more than exercises for our imagination. But they are more than this, as can be seen from the fact that we submit them to severe tests by trying to deduce from them some of the regularities of the known world of common experience--i.e. by trying to explain these regularities. And these
attempts to explain the known by the unknown (as I have described them elsewhere 11 ) have immeasurably extended the realm of the known. They have added to the facts of our everyday world the invisible air, the antipodes, the circulation of the blood, the worlds of the telescope and the microscope, of electricity, and of tracer atoms
showing us in detail the movements of matter within living bodies. All these things are far from being mere instruments: they are witness to the intellectual conquest of our world by our minds.
But there is another way of looking at these matters. For some, science is still nothing but glorified plumbing, glorified gadget-making--'mechanics'; very useful, but a danger to true culture, threatening us with the domination of the near-illiterate (of Shakespeare's 'mechanicals'). It should never be mentioned in the same breath as literature or the arts or philosophy. Its professed discoveries are mere mechanical inventions, its theories are instruments--gadgets again, or perhaps super-gadgets. It cannot and does not reveal to us new worlds behind our everyday world of appearance; for the physical world is just surface: it has no depth. The world is just what it appears to be. Only the
scientific theories are not what they appear to be. A scientific theory neither explains nor describes the world; it is nothing but an instrument.
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10 Salviati says so several times, with hardly a verbal variation, on the Third Day of The Two Principal Systems.
11 See the Appendix, point (10) to ch. 1, above, and the penultimate paragraph of ch. 6, below.
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I do not present this as a complete picture of modern instrumentalism, although it is a fair sketch, I think, of part of its original philosophical background. Today a much more important part of it is, I am well aware, the rise and self-assertion of the modern 'mechanic' or engineer. 12 Still, I believe that the issue should be seen to lie between a critical and adventurous rationalism--the spirit of discovery--and a narrow and defensive creed according to which we cannot and need not learn or understand more about our world than we know already. A creed, moreover, which is incompatible with the appreciation of science as one of the greatest achievements of the human spirit.Such are the reasons why I shall try, in this paper, to uphold at least part of the Galilean view of science against the instrumentalist view. But I cannot uphold all of it. There is a part of it which I believe the instrumentalists were right to attack. I mean the view that in science we can aim at, and obtain, an ultimate explanation by essences. It is in its opposition to this Aristotelian view (which I have called 13 'essentialism') that the strength and the philosophical interest of instrumentalism lies. Thus I shall have to discuss and criticize two views of human knowledge--essentialism and instrumentalism. And I shall oppose to them what I shall call the third view--what remains of Galileo's view after the elimination of essentialism, or more precisely, after allowance has been made for what was justified in the
instrumentalist attack.